i have a 97 ford expedition with a 4.6 4x4 on 33's about 160k... i just bought it a few weeks ago... i have done a tune up with iridium plugs new wires,,, oil/tranny fluid changed along with filters... egr coolant flush.. and fixed any vacuume lines that looked rotted i changed... i also put 2 cats on it the others where blown out and i cut off the muffler there was toooo much back pressure ... i have a loss of power mostly no torque and no top end power its great off the line but thats it... on top of that my coolant kind of smells like gas im not sure what that means but the oil is clean no water in it... i get like 7mpg if i drive it regular and granny driving i get 10. o yeah when we did the tune up i noticed water on the no4 plug so im assumeing thats why my water smells like exhaust???? please help..

 

You say you changed the tires to 33's. What gears are in the axles?
Did you compensate for the tire size change for the speedometer in any way?
JL

 

as far as the gears go i think there stock gears ....tires came with the truck like that he didnt mention anything about replacing gears in fact he said that he bought the truck like that all he did was replace tires because the others were worn .... @ 65mph im at or around 2k rpms maybe a lil less

 

Well, that's a portion of your fuel mileage "problem". Your current tires are taller than the OEM tires,and if you do not correct the speedometer for the size difference-the odometer will be off-showing fewer miles than you've actually traveled. This will make it appear that you're getting worse fuel mileage than you are.
JL

 

Was it a stock muffler you cut off? I'm curious as to how it had way too much backpressure. The only way it would have too much is if the catalytic converters were clogged up but you addressed that issue. Try putting a freer flowing muffler on it. That and has the truck always run like this or did it start a while after you bought it?

 

Before you get going any further, I would troubleshoot the coolant in the #4 cylinder. Sounds like a possible head gasket.

 

I'm thinking that maybe when you flushed the coolant you might have flushed some stop leak loose

 

to start i took it in to find out why it sounded so bad it had a wierd noise when i punched it kind of like if water was comming out of it like when you start a jet ski but not as bad.... act no where near as bad but thats the way it sounded if that makes any sence but i also had no power so i took it in and they said it was my muffler....
it had a dynamax on it then... so i purchaced a reg. turbo muffler from them and when down the road and it still made the same sound so i purchased 2 cats had them put them on and it was the same took my mechanic for a ride he said that there was to much back pressure so i cut off the muffler and told them to just pipe it in and refund my money for the muffler to fix the gap in the pipe.... so no i do have more power than before but it still has that sound like something is clogged i did cut the pipes in dif places and ran a snake threw them no clogs ...

 

i think that might be the whole problem with it ..... ive been told by 3 people now that is what it is im not sure if i posted it before but the coolant smells like exhuast fumes,,,,,,